7129284: +DoEscapeAnalysis regression w/ early build of 7u4 (HotSpot 23) on Linux

Summary: Removed code which tried to create edges from fields of destination objects of arraycopy to fields of source objects. Added 30 sec time limit for EA graph construction.
Reviewed-by: never

src/share/vm/opto/escape.cpp

 /*
- * Copyright (c) 2005, 2011, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2005, 2012, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -1687,12 +1687,23 @@ bool ConnectionGraph::compute_escape() {
   // Observed 8 passes in jvm2008 compiler.compiler.
   // Set limit to 20 to catch situation when something
   // did go wrong and recompile the method without EA.
+  // Also limit build time to 30 sec (60 in debug VM).
 
 #define CG_BUILD_ITER_LIMIT 20
 
+#ifdef ASSERT
+#define CG_BUILD_TIME_LIMIT 60.0
+#else
+#define CG_BUILD_TIME_LIMIT 30.0
+#endif
+
   uint length = worklist.length();
   int iterations = 0;
-  while(_progress && (iterations++ < CG_BUILD_ITER_LIMIT)) {
+  elapsedTimer time;
+  while(_progress &&
+        (iterations++   < CG_BUILD_ITER_LIMIT) &&
+        (time.seconds() < CG_BUILD_TIME_LIMIT)) {
+    time.start();
     _progress = false;
     for( uint next = 0; next < length; ++next ) {
       int ni = worklist.at(next);
@@ -1701,18 +1712,19 @@ bool ConnectionGraph::compute_escape() {
       assert(n != NULL, "should be known node");
       build_connection_graph(n, igvn);
     }
+    time.stop();
   }
-  if (iterations >= CG_BUILD_ITER_LIMIT) {
-    assert(iterations < CG_BUILD_ITER_LIMIT,
-           err_msg("infinite EA connection graph build with %d nodes and worklist size %d",
-           nodes_size(), length));
+  if ((iterations     >= CG_BUILD_ITER_LIMIT) ||
+      (time.seconds() >= CG_BUILD_TIME_LIMIT)) {
+    assert(false, err_msg("infinite EA connection graph build (%f sec, %d iterations) with %d nodes and worklist size %d",
+           time.seconds(), iterations, nodes_size(), length));
     // Possible infinite build_connection_graph loop,
-    // retry compilation without escape analysis.
-    C->record_failure(C2Compiler::retry_no_escape_analysis());
+    // bailout (no changes to ideal graph were made).
     _collecting = false;
     return false;
   }
 #undef CG_BUILD_ITER_LIMIT
+#undef CG_BUILD_TIME_LIMIT
 
   // 5. Propagate escaped states.
   worklist.clear();
@@ -2292,9 +2304,35 @@ void ConnectionGraph::process_call_arguments(CallNode *call, PhaseTransform *pha
         PointsToNode::EscapeState arg_esc = ptnode_adr(arg->_idx)->escape_state();
         if (!arg->is_top() && at->isa_ptr() && aat->isa_ptr() &&
             (is_arraycopy || arg_esc < PointsToNode::ArgEscape)) {
-
+#ifdef ASSERT
           assert(aat == Type::TOP || aat == TypePtr::NULL_PTR ||
                  aat->isa_ptr() != NULL, "expecting an Ptr");
+          if (!(is_arraycopy ||
+                call->as_CallLeaf()->_name != NULL &&
+                (strcmp(call->as_CallLeaf()->_name, "g1_wb_pre")  == 0 ||
+                 strcmp(call->as_CallLeaf()->_name, "g1_wb_post") == 0 ))
+          ) {
+            call->dump();
+            assert(false, "EA: unexpected CallLeaf");
+          }
+#endif
+          if (arg_esc < PointsToNode::ArgEscape) {
+            set_escape_state(arg->_idx, PointsToNode::ArgEscape);
+            Node* arg_base = arg;
+            if (arg->is_AddP()) {
+              //
+              // The inline_native_clone() case when the arraycopy stub is called
+              // after the allocation before Initialize and CheckCastPP nodes.
+              // Or normal arraycopy for object arrays case.
+              //
+              // Set AddP's base (Allocate) as not scalar replaceable since
+              // pointer to the base (with offset) is passed as argument.
+              //
+              arg_base = get_addp_base(arg);
+              set_escape_state(arg_base->_idx, PointsToNode::ArgEscape);
+            }
+          }
+
           bool arg_has_oops = aat->isa_oopptr() &&
                               (aat->isa_oopptr()->klass() == NULL || aat->isa_instptr() ||
                                (aat->isa_aryptr() && aat->isa_aryptr()->klass()->is_obj_array_klass()));
@@ -2307,85 +2345,33 @@ void ConnectionGraph::process_call_arguments(CallNode *call, PhaseTransform *pha
           //   arraycopy(char[],0,Object*,0,size);
           //   arraycopy(Object*,0,char[],0,size);
           //
-          // Don't add edges from dst's fields in such cases.
+          // Do nothing special in such cases.
           //
-          bool arg_is_arraycopy_dest = src_has_oops && is_arraycopy &&
-                                       arg_has_oops && (i > TypeFunc::Parms);
-#ifdef ASSERT
-          if (!(is_arraycopy ||
-                call->as_CallLeaf()->_name != NULL &&
-                (strcmp(call->as_CallLeaf()->_name, "g1_wb_pre")  == 0 ||
-                 strcmp(call->as_CallLeaf()->_name, "g1_wb_post") == 0 ))
-          ) {
-            call->dump();
-            assert(false, "EA: unexpected CallLeaf");
-          }
-#endif
-          // Always process arraycopy's destination object since
-          // we need to add all possible edges to references in
-          // source object.
-          if (arg_esc >= PointsToNode::ArgEscape &&
-              !arg_is_arraycopy_dest) {
-            continue;
-          }
-          set_escape_state(arg->_idx, PointsToNode::ArgEscape);
-          Node* arg_base = arg;
-          if (arg->is_AddP()) {
-            //
-            // The inline_native_clone() case when the arraycopy stub is called
-            // after the allocation before Initialize and CheckCastPP nodes.
-            // Or normal arraycopy for object arrays case.
-            //
-            // Set AddP's base (Allocate) as not scalar replaceable since
-            // pointer to the base (with offset) is passed as argument.
-            //
-            arg_base = get_addp_base(arg);
-          }
-          VectorSet argset = *PointsTo(arg_base); // Clone set
-          for( VectorSetI j(&argset); j.test(); ++j ) {
-            uint pd = j.elem; // Destination object
-            set_escape_state(pd, PointsToNode::ArgEscape);
-
-            if (arg_is_arraycopy_dest) {
-              PointsToNode* ptd = ptnode_adr(pd);
-              // Conservatively reference an unknown object since
-              // not all source's fields/elements may be known.
-              add_edge_from_fields(pd, _phantom_object, Type::OffsetBot);
-
-              Node *src = call->in(TypeFunc::Parms)->uncast();
-              Node* src_base = src;
-              if (src->is_AddP()) {
-                src_base  = get_addp_base(src);
-              }
-              // Create edges from destination's fields to
-              // everything known source's fields could point to.
-              for( VectorSetI s(PointsTo(src_base)); s.test(); ++s ) {
-                uint ps = s.elem;
-                bool has_bottom_offset = false;
-                for (uint fd = 0; fd < ptd->edge_count(); fd++) {
-                  assert(ptd->edge_type(fd) == PointsToNode::FieldEdge, "expecting a field edge");
-                  int fdi = ptd->edge_target(fd);
-                  PointsToNode* pfd = ptnode_adr(fdi);
-                  int offset = pfd->offset();
-                  if (offset == Type::OffsetBot)
-                    has_bottom_offset = true;
-                  assert(offset != -1, "offset should be set");
-                  add_deferred_edge_to_fields(fdi, ps, offset);
-                }
-                // Destination object may not have access (no field edge)
-                // to fields which are accessed in source object.
-                // As result no edges will be created to those source's
-                // fields and escape state of destination object will
-                // not be propagated to those fields.
-                //
-                // Mark source object as global escape except in
-                // the case with Type::OffsetBot field (which is
-                // common case for array elements access) when
-                // edges are created to all source's fields.
-                if (!has_bottom_offset) {
-                  set_escape_state(ps, PointsToNode::GlobalEscape);
-                }
-              }
+          if (is_arraycopy && (i > TypeFunc::Parms) &&
+              src_has_oops && arg_has_oops) {
+            // Destination object's fields reference an unknown object.
+            Node* arg_base = arg;
+            if (arg->is_AddP()) {
+              arg_base = get_addp_base(arg);
+            }
+            for (VectorSetI s(PointsTo(arg_base)); s.test(); ++s) {
+              uint ps = s.elem;
+              set_escape_state(ps, PointsToNode::ArgEscape);
+              add_edge_from_fields(ps, _phantom_object, Type::OffsetBot);
+            }
+            // Conservatively all values in source object fields globally escape
+            // since we don't know if values in destination object fields
+            // escape (it could be traced but it is too expensive).
+            Node* src = call->in(TypeFunc::Parms)->uncast();
+            Node* src_base = src;
+            if (src->is_AddP()) {
+              src_base  = get_addp_base(src);
+            }
+            for (VectorSetI s(PointsTo(src_base)); s.test(); ++s) {
+              uint ps = s.elem;
+              set_escape_state(ps, PointsToNode::ArgEscape);
+              // Use OffsetTop to indicate fields global escape.
+              add_edge_from_fields(ps, _phantom_object, Type::OffsetTop);
             }
           }
         }